Nasopharyngeal carcinoma: histopathological types and association with Epstein-Barr Virus

Virus-associated neoplasms of the nasopharynx and sinonasal tract: diagnostic problems

A significant fraction of nasopharyngeal and sinonasal tumors are associated with Epstein-Barr virus (EBV) or human papillomavirus (HPV). Nasopharyngeal carcinoma (NPC) and extranodal NK/T-cell lymphoma harbor EBV in practically all cases, although a small proportion of cases of the former harbor HPV. Sinonasal inverted papillomas harbor HPV in about 25% of cases. Sinonasal squamous cell carcinomas harbor transcriptionally active HPV in about 20% of cases, and limited data suggest that this subset has a better prognosis than the HPV-negative subset. This review addresses the diagnostic issues of the EBV-associated tumors. Difficulties in diagnosis of NPC may be encountered when there are prominent crush artifacts, many admixed lymphoid cells masking the neoplastic cells, or numerous interspersed granulomas, whereas benign cellular components (epithelial crypts and germinal centers) and reactive lymphoid hyperplasia can potentially be mistaken for NPC. Immunostaining for pan-cytokeratin and/or in situ hybridization for EBER can help in confirming or refuting a diagnosis of NPC. The main diagnostic problem of extranodal NK/T-cell lymphoma is recognition of the neoplastic nature of those examples predominated by small cells or showing a mixture of cells. The identification of a destructive infiltrate (dense expansile infiltrate; angiocentric growth) and definite cytologic atypia (clear cells; many medium-sized cells) would favor a diagnosis of lymphoma, which can be supported by immunohistochemistry (most commonly CD3+, CD5-, CD56+) and in situ hybridization for EBER. In conclusion, among nasopharyngeal and sinonasal neoplasms, demonstration of EBV may aid in diagnosis, particularly NPC and extranodal NK/T-cell lymphoma. Demonstration of HPV does not have a role yet in diagnosis, although this may change in the future.

Human papillomavirus 16 detected in nasopharyngeal carcinomas in white Americans but not in endemic Southern Chinese patients

BACKGROUND

We evaluated the relationship of human papillomavirus (HPV) and Epstein-Barr virus (EBV) with race in endemic and nonendemic cohorts of patients with nasopharyngeal carcinoma (NPC), and with smoking status in the nonendemic cohort.

METHODS

Tissue microarrays (TMAs) were constructed using samples from 86 patients treated in southern China and 108 patients from Stanford, California. TMAs were stained with p16, HPV in situ hybridization (ISH), and EBV ISH. Polymerase chain reaction (PCR) was used to confirm EBV(-) cases and HPV status in p16(+) cases. Survival data was available for the Stanford cohort only.

RESULTS

No HPV(+) cases were detected in the Chinese cohort. In the Stanford cohort, 5 of 11 EBV(-) cases harbored HPV-16, 10 of 10 occurred in whites, and 8 of 11 were smokers. Patients with EBV(-) NPC also showed a trend toward worse survival.

CONCLUSION

EBV(-) NPC shows an association with the presence of HPV, white race, and smoking. In contrast, EBV(-) NPC shows no association with HPV in the endemic cohort.

Aberrant activation of hedgehog pathway in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a very common head and neck cancer in southern china. Despite advances in surgical and chemotherapeutic approaches, its prognosis is still not promising. Hedgehog signaling pathway was reported to be involved in a number of cancers including head and neck. However, it remains unclear regarding the role of this pathway in NPC. By real-time PCR, we found Ptch1, Smo, and Gli-1 were expressed in all human nasopharyngeal epithelial tissues and cell lines. Compared with nasopharyngeal normal epithelial tissues, the mRNA expression level of Gli-1 was higher in carcinoma and nasopharyngitis (NPI) epithelial tissues. While compared with nasopharyngitis epithelia, the mRNA expression level of Ptch1 was lower in carcinoma epithelia and normal epithelia. The expressions of Smo mRNA were not significantly different among these epithelial tissues. Immunohistochemistry analysis revealed that the expression level of Gli-1 was higher in NPC than NPI. Thus, our data indicated that aberrant activation of hedgehog pathway in NPC. Furthermore, blocking the pathway with cyclopamine inhibited the proliferation of NPC epithelia cell lines. In addition, blockade of the pathway in three NPC cell lines with cyclopamine-induced tumor cell apoptosis. The transcription of hedgehog target genes also is inhibited by cyclopamine. These data suggested that hedgehog pathway may sustain nasopharyngeal tumor growth. Our data demonstrated that hedgehog signaling pathway was involved in NPC pathogenesis and might be a novel therapeutic target for NPC.

ZEB1 and c-Jun levels contribute to the establishment of highly lytic Epstein-Barr virus infection in gastric AGS cells

The induction of lytic infection has been proposed as a therapeutic strategy for treating Epstein-Barr virus (EBV)-positive malignancies. To succeed, efficient methods are needed for activating the EBV immediate-early (IE) promoters, Zp and Rp. Here we compared factors which regulate Zp and Rp in AGS gastric carcinoma cells that support a remarkably high level of persistently lytic EBV infection with HeLa cervical cells that permit only tightly latent infection. We found that the level of Zp activity assayed by transient transfection assays with reporter plasmids was high in AGS cells but low in HeLa cells. The level of Rp activity was low in both cell types. Mutational analysis indicated that sequences within Zp located between -70 and +27 relative to the transcription initiation site were sufficient to confer a high level of Zp activity in AGS cells. The Zp CRE motif was necessary for this constitutive activity, while the ZIA and ZIB MEF2D motifs were not. Consistent with these findings, immunoblot analysis indicated that phosphorylated c-Jun, which activates Zp through the CRE motif, was expressed at a much higher level in EBV-infected AGS cells than in EBV-infected HeLa cells. In contrast, ZEB1, which represses Zp via the ZV motif located near the transcription initiation site, was abundant in HeLa cells, while it was absent from AGS cells. Exogenous addition of ZEB1 led to the repression of Zp in AGS cells. We conclude that the unusually high Zp activity level in AGS cells is due to the high abundance of positively acting transcription factors such as c-Jun combined with the low abundance of negatively acting factors such as ZEB1.

The expression of p63 is associated with the differential stage in nasopharyngeal carcinoma and EBV infection

Background

Nasopharyngeal carcinoma (NPC) is common among Southern Chinese and the main histology is the undifferentiated carcinoma associated with Epstein-Barr virus (EBV) infection. p63 is a recently proved member of the p53 family based on the structural similarity to p53, but its function in NPC is still unknown. This study was aimed to investigate the association between p63 and NPC.

Results

p63 was expressed in 100%(202/202) of nasopharyngeal carcinoma (NPC) tissues but not in 29 nasopharynx inflammation and 17 non-cancerous nasopharyngeal epidermises on a tissue microarray by immunohistostaining. Further investigation suggested that the p63 expression was associated with the differential stage of NPC: p63 strong staining in Keratinizing squamous cell carcinoma, differentiated non-keratinizing NPC and undifferentiated non-keratinizing NPC presented the percentage of 5/8 (62.5%), 43/48 (92.5%) and 50/50 (100%), respectively. A significant difference (p = 0.001) existed between the keratinizing and non-keratinizing groups. No pathogenic mutations were detected in p63 gene in 12 primary NPC tissues and matched peripheral blood lymphocytes (PBL). Half-life measurement study revealed distinct stability of p63 protein in the different cell lines, especially between the carcinoma cell lines with EBV infection and the non-cancerous cell lines. The results of immunoprecipitation suggested a direct interaction between Epstein-Barr virus nuclear antigen 5 (EBNA-5) and p63 protein in NPC, and this binding would increase the stability of p63.

Conclusion

Our data suggested p63 might be used as an adjunct diagnostic marker of NPC and contributed a new way to understand the contribution of the EBV in the pathogenesis of NPC.

Epstein-Barr virus-associated carcinomas: facts and fiction

The Epstein-Barr virus (EBV) is associated with several human tumours including lymphoid and epithelial malignancies. Most EBV-associated tumours are rare or occur at higher incidence only in certain geographical regions. The recently reported detection of EBV in gastric, breast, and hepatocellular carcinomas raises the possibility of involvement of the virus in the pathogenesis of common cancers. This article reviews the evidence linking EBV infection to epithelial tumours. It is concluded that at present, there is no convincing evidence to suggest that breast carcinoma and hepatocellular carcinoma are EBV-associated tumours.

Association of Epstein-Barr virus and nasopharyngeal carcinoma in Caucasian patients

We evaluated the association of nasopharyngeal carcinoma (NPC) and Epstein-Barr virus (EBV) in Spanish patients, and studied the expression of EBV products (latent membrane protein-1 [LMP-1] and ZEBRA proteins) by NPC cells and its possible prognostic value. In situ hybridization (ISH) for EBV-encoded nonpolyadenylated RNAs (EBERs) and immunohistochemical expression of LMP-1 and ZEBRA proteins by immunohistochemistry were examined in formalin-fixed, paraffin-embedded NPC specimens from 30 patients, and a survival analysis was done by the Kaplan-Meier method. We detected EBERs by ISH in 96.67% of the NPC cases, and detected expression of LMP-I in 43.33% of the NPC cases and expression of ZEBRA protein in 6.67% of the NPC cases. We conclude that ISH for expression of EBERs is an adequate method for detection of EBV in NPC. LMP-1 is not frequently expressed in NPC cells (43.33%). Most NPC cells carry a latent EBV infection. LMP-1 expression might have worsened the prognosis of NPC in our series.

Epstein-Barr virus infection in the pathogenesis of nasopharyngeal carcinoma

The association of nasopharyngeal carcinoma (NPC) with the Epstein-Barr virus (EBV) was firmly established as early as 1973. Nevertheless, the role for the virus in the pathogenesis of NPC is still controversial. In this article, the evidence implicating EBV in the development of NPC is reviewed, focusing on the cellular site of EBV persistence, the association of the virus with different NPC histotypes, the tumour cell phenotype in the context of viral latent gene expression, and the possible role of the lymphoid stroma.

Apoptosis-related genes and proteins in Hodgkin's disease

During recent years it has become increasingly evident that L&H cells in nodular lymphocytic predominance (LP) Hodgkin's disease (HD) and Hodgkin and Reed-Sternberg (H-RS) cells in approximately half the cases of classical HD originate from B-lymphocytes, and that H-RS cells in most of the remaining cases of classical HD express a null phenotype. The pathogenesis of HD is unknown. An association with Epstein-Barr virus (EBV) has been suggested and there are also indications that genes involved in programmed cell death (apoptosis) may be implicated. In this study, the expression of four apoptosis-related proteins (bcl-2, bcl-x, bax and p53) in 53 cases of HD was examined and the data were correlated with the genotype, the EBV status and the phenotype (B, T or null) of the neoplastic cells. The H-RS cells expressed a B-cell phenotype in 3/3 cases of nodular LP and in 19/ 50 (38%) cases of classical HD. The remaining cases showed a null-cell phenotype in 29/50 (58%) and a T-cell phenotype in 2/50 (4%). EBV was more often positive in B (14/19, 74%) than in null (7/29, 24%) type HD. The H-RS cells were bcl-2-positive in 19/53 (36%), bcl-x-positive in 17/53 (32%), bax-positive in 1/53, and p53-positive in 41/53 (77%) cases. No relationship was found between bcl-2 expression and EBV status, or between bcl-2 and bcl-x expression. A t(14;18) translocation was seen in 2 of 34 cases. P53 point mutations were not detected. Our findings indicate that nodular LP and classical HD originate from B-cells in a high proportion of cases. They also suggest a role for bcl-2, bcl-x and p53 in tumorigenesis. The pathogenesis is not known at this stage.

Nasopharyngeal swab and PCR for the screening of nasopharyngeal carcinoma in the endemic area: a good supplement to the serologic screening

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a common head and neck cancer in Taiwan. Early detection is the best way to improve survival for this disease. A prospective study was designed to assess the feasibility of a new screening method for NPC by use of polymerase chain reaction (PCR) based on the close association of NPC and Epstein-Barr virus (EBV).

METHODS

One hundred thirty-three different tissues from nasopharynx, nose, and sinus were investigated by use of PCR to check for the presence of EBV genome. Subsequently, from April 1996 to March 1997, 55 patients were enrolled in a prospective screening study. All patients underwent nasopharyngeal swabs before biopsy. Polymerase chain reaction detection of EBV genome was conducted on swab samples. Anti-EBV viral capsid antigen (VCA) in IgA and IgG class were checked at the same visit.

RESULTS

The EBV genome was present in 91.4% (85/93) of NPC tissues and in 25.0% (10/40) of non-NPC tissues (p < .001, chi2 test). Of the 55 swabs, 49 (89.1%) specimens obtained enough cells for PCR examination. Thirty of these 49 patients were pathologically proved NPC. The presence of EBV were 86.7% (26/30) in NPC group and 42.1% (8/19) in non-NPC group. The sensitivity and specificity were 86.7% and 57.9%, respectively, which were similar to those of serologic method (87.5% and 43.5%) when the cut-off point was set at anti-VCA IgG > or = 160 and IgA > or = 10. Combining both methods elevates the specificity to 84.2%.

CONCLUSIONS

The sensitivity of this PCR screening method is similar to that of the serologic method. Combining both methods can greatly increase the specificity, indicating this new method is a good supplement to the serologic screening of this endemic disease.

Fine-needle aspiration cytology of metastatic nasopharyngeal carcinoma

Over a 32-month period at the University Hospital, Kuala Lumpur, we were able to study the cytological appearance of metastatic nasopharyngeal carcinoma (NPC) in 17 cases. This comprised 14 males and three females of which 13 were Chinese, three were Malay, and one was Indian. Their ages ranged from 27 to 64 years. Histological correlation was available in all the patients in the form of nasopharyngeal biopsies, and they were classified as per the World Health Organization classification into types I, II, and III NPC. Smears from type II NPC showed good cellularity with mainly clustered and occasionally dissociated cells, with focal columnar appearance, vesicular nuclei, prominent nucleoli, and variable amounts of cytoplasm. Clusters of malignant cell closely associated with lymphoid cells and dissociation of malignant cells were more characteristic of type III NPC. FNA cytology is now applied extensively to the diagnosis of head and neck tumours and knowledge of the cytomorphology of NPC would greatly aid in pinpointing the primary of this tumour which is notorious for presenting with early nodal metastasis.

Epstein-Barr virus expression within keratinizing nasopharyngeal carcinoma

Three stages of maturation can be seen in keratinizing nasopharyngeal carcinomas. These stages are similar morphologically to basal cells, intermediate and superficial squamous cells seen in normal squamous epithelium. Taking advantage of such a diverse tumour cell population, 10 keratinizing nasopharyngeal carcinoma (NPC) were examined by in situ hybridization for the presence of latent Epstein-Barr Virus (EBV) using EBV encoded RNAs (EBERs) and by immunohistology for the presence of EBV early antigen-diffuse (EA-D) and the 350/220 kd membrane glycoprotein of the EBV. The basal cell-like tumour cells are mainly infected latently with the virus; viral replication was found in isolated intermediate squamous cells, whilst superficial squamous cells are largely depleted of all the viral markers. We used a control series of nonkeratinizing nasopharyngeal carcinomas composed of undifferentiated and poorly differentiated tumour cells and EBV latency was present in these tumours. Viral replication was detected by RT-PCR, in the undifferentiated tumours but viral replication was not seen by immunohistology. The possible relationship between EBV life cycle in these tumours and tumour cell differentiation is discussed in the light of these findings.

Comparative analysis of Epstein-Barr virus (EBV) detection by nested-PCR and non-isotopic in situ hybridization in nasopharyngeal carcinoma (NPC)

The aims of this study were two-fold: first, to assess the relative diagnostic performance of non-isotopic in situ hybridization (ISH) and the nested polymerase chain reaction (nested-PCR) applied to Epstein-Barr virus (EBV) detection in a series of 55 unselected nasopharyngeal carcinoma (NPC) cases and, secondly, to correlate these data with histopathological classification. Our study shows that in 76.36% of NPC cases positive nuclear signals were observed using EBV-ISH. Overall, EBV-ISH positivity varied according to histological type, in that undifferentiated carcinomas showed a higher proportion of positive cases than differentiated cell carcinomas, although ISH results do not show significant differences in relation to histological types when employing two different schemes (WHO and Micheau). However, in adequate quality DNA samples (54 NPC cases), EBV-DNA was detected in 100% of cases using a nested-PCR, supporting the previous view that all histological types of NPC are in reality variants of EBV-infected neoplasia. ISH-negative cases probably reflect a lower sensitivity than PCR, particularly when a small number of viral copies are present, as well as a variable technical effectiveness for detected EBV, independent of the NPC histological type.

The association of squamous cell carcinomas of the nasopharynx with Epstein-Barr virus shows geographical variation reminiscent of Burkitt's lymphoma

Nasopharyngeal carcinoma (NPC) is rare in most parts of the world but occurs with high incidence in certain regions, such as South-East Asia. Two major histological types of NPC are recognized, non-keratinizing carcinoma and squamous cell carcinoma. Non-keratinizing NPCs, which include undifferentiated NPC, are invariably associated with Epstein-Barr virus (EBV) infection, regardless of the geographical or ethnic origin of the patients. By contrast, conflicting results have been published concerning a possible association of squamous cell NPC with the virus. To address this question, squamous cell NPCs have been collated from an area where NPC is endemic, Hong Kong, and from two regions where NPC occurs with a lower incidence, Chengdu, PR China, and Birmingham, United Kingdom. In situ hybridization for the detection of the small EBV-encoded nuclear RNAs (EBERs) demonstrated that all 22 cases from Hong Kong were EBV-positive. By contrast, EBV was detectable in 7 of 19 cases from central China, and in 3 of 7 cases from the U.K. Expression of the virus-encoded latent membrane protein 1 (LMP1) was detected in 3 of 32 EBV-positive squamous cell NPCs. These results indicate that the association of squamous cell NPCs with EBV shows geographical variability in a manner which is reminiscent of the situation encountered in Burkitt's lymphoma. This suggests that squamous cell NPCs are a pathogenetically heterogeneous group of tumours distinct from non-keratinizing NPCs.

Immunohistochemical expression of Epstein-Barr virus-encoded latent membrane protein (LMP-1) in paraffin sections of EBV-associated nasopharyngeal carcinoma in Spanish patients

Nasopharyngeal carcinoma (NPC) paraffin samples, from Spanish patients, of distinct histological types, including squamous cell carcinoma (10 cases), nonkeratinising carcinoma (12 cases) and undifferentiated carcinoma (29 cases) were analysed for Epstein-Barr virus (EBV) detection and EBV-encoded latent membrane protein (LMP-1) expression using a sensitive nested-polymerase chain reaction with four oligonucleotide primers specific for EBV genome (EB-1, 2, 3, 4) and immunohistochemistry by means of CS1-4 pool monoclonal antibody. EBV genome was detected regardless of histological type in 100% of samples with sufficient DNA quality to permit viral diagnosis (50 out of 51 cases), supporting the previous view that all types of NPC are variants of an EBV-associated malignancy. However LMP-1, an EBV-encoded oncogenic protein, was detected in 40 out of 51 samples (78.4%) and LMP-1 immunohistochemical expression was not apparently influenced by histological type, primary or metastatic site, clinical stage, age or sex. This high percentage of detection of LMP-1 in our cases supports a role for EBV in the pathogenesis of different types of NPC, but the lack of constant expression of LMP-1 in NPC remains unclear and various reasons are postulated to explain the absence of this oncogenic protein in some EBV-associated NPCs.

Epstein-Barr virus is detected in undifferentiated nasopharyngeal carcinoma but not in lymphoepithelioma-like carcinoma of the urinary bladder

The Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC) and with lymphoepithelioma-like carcinomas developing in certain anatomic sites. In this study, an in situ hybridization was used to identify EBV-encoded ribonucleic acid (RNA) (EBER1) transcripts in 32 of 45 cases of NPC but not in any of the 11 lymphoepithelioma-like carcinomas developing in the urinary bladder. EBER1 was most commonly detected in those NPCs having undifferentiated or nonkeratinizing squamous histology rather than the keratinizing squamous cell subtype of NPC. The EBV-encoded latent membrane protein 1 (LMP1) was expressed focally in only seven of 21 EBER1-positive NPCs by an immunohistochemical technique. These findings imply that EBER1 hybridization is more sensitive than LMP1 immunohistochemistry on paraffin sections in detecting carcinoma-associated virus. Previous in vitro studies have suggested that LMP1 expression might be a function of differentiation, but this study of naturally infected NPCs showed no strong correlation between LMP1 positivity and degree of tumor differentiation, albeit a limited spectrum of differentiation that could be examined. In two cases in which frozen tissue was available, the NPCs were monoclonal with respect to viral DNA structure, implying that the virus was present before malignant transformation. Unlike NPCs, the lymphoepithelioma-like carcinomas of the bladder were uniformly EBV negative, lending further evidence to the growing body of literature linking EBV with lymphoepithelial carcinomas of foregut-derived tissues but not with similar-appearing tumors developing in other anatomic sites.

Epstein-Barr virus and Hodgkin's disease: a comparative immunological, in situ hybridization, and polymerase chain reaction study

During recent years numerous studies have demonstrated the presence of Epstein-Barr virus (EBV) in tissues affected by Hodgkin's disease (HD). The percentage of cases with evidence of EBV infection has varied among the different studies, a positive result being highly dependent on the sensitivity of the method employed. In this study three different methods of detecting EBV in 48 cases of 'classical' HD (33 cases of nodular sclerosis and 15 cases of mixed cellularity) were compared: Immunohistochemistry (IH) for detection of latent membrane protein-1 (LMP-1), in situ hybridization (ISH) for detection of Epstein-Barr virus early RNAs (EBER 1 and 2), and polymerase chain reaction (PCR) for detection of a reiterated 110 base-pair EBV genomic sequence of the BamHI region. In 14 cases (29%) Hodgkin's (H) and Reed-Sternberg (RS) cells were positive for LMP-1 using IH, and in 21 cases (44%) positive signals were seen in H-RS cells with EBER 1 and 2 probes using ISH. A few EBER-positive non-malignant lymphocytes were seen in 17 cases. Thirty-two cases (71%) were EBV-positive by PCR. It is concluded that the PCR technique is the most sensitive method for detecting EBV in HD. However, this method cannot provide information about the cellular localization of EBV. ISH with EBER 1 and 2 probes is superior to immunohistochemical detection of LMP-1 with regard to sensitivity. The advantage that the latter two methods have over the PCR techniques is that it is possible to analyse whether the EBV infection occurs in the H-RS cells or in the admixed non-malignant cell population. Furthermore, this study supports the observation that EBV is associated with a considerable number of HD cases.